Method for the separation of gases, &amp;c.



R. J. LE' Y & A. HELBRONNER. METHOD FOR THE SEPARATION OF GASES, 6w.

APPLICATION FILED PIIBJB, 1903.

Patented May 31, 1910. I

2 SHEBTB-SHEET 1.

K B W/ INVENTQRS.

ETNESSES. I a 1 fl W v 1 v R. J. LEVY & A. HELBRONNER. METHOD FOR THESEPARATION OF GASES, duo. APPLICATION FILED IEB.16. 1903.

9,53. I Patented May 31,1910.

2 SHEETS-SHEET 2.

A TED STATES PATENT OFFICE.

RENE JACQUES LEVY, or MANCHESTER, ENGLAND, AND ANDRE HELBRCNNE'R, or

PARIs, FRANCE.

Specification of Letters Patent.

Patented May 31, 1910.

Application filed February 16, 1903. Serial No. 143,703.

To all whom it may concern:

Be it known that we, RENE JAC UES LE'vY, a French citizen, and residentof Manchester, in the county of Lancaster, England, and ANDREHELBRONNER, a French citizen, and resident of Paris, in the Republic ofFrance, have invented certain new and useful Improvements in Methods forthe Separation of Gases, &c., of which the followlng is a specification.

This invention relates to improvements in the separation of gases fromtheir mixtures, more especially the separation of oxygen and nitrogenfrom atmospheric air, for the purpose of obtaining free oxygen and freenitrogen.

The process will be described with reference to the separation of oxygenfrom nitrogen, but it is to be understood that the same process isapplicable to other mixed gases.

It has been known since the year 1884, that air boils at -176 C., undera pressure of 4 atmospheres and that it boils at about 192 C. atatmospheric pressure (see Olzewski Oomptes Remlus de ZAcademie alesSciences, vol. 99, page 184.). From this it follows that air can beliquefied at temperatures between about -176 0., and --192 (3., atpressures varying from 15 up to 60 lbs. per square inch. We make use ofthis knowledge and these facts to first liquefy the air during ourprocess of separating it intoits constituent elements.

The inventionwill be fully described with reference to the accompanyingdrawings Figure 1, sectional elevation of apparatus in which the processis carried out. Fig. 2, sectional plan on line mm Fig. 1. Fig. 3,sectional plan on line yg Fig. 4, sectional plan on line zz. Theapparatus is constructed in the form of a tower divided into two maincompartments, by a division plate or partition X, and the compartmentsabove and below the partition X, into any number of small chambers bythe plates or trays D D D etcetera. We have shown only a limited numberofsuch chambers below the partition X, and above it; (the drawing isshown broken because of the limited space.) The plates or trays D, D, Detcetera, are provided with a passage or passages E through which thegas travels upward and also with a passage or passages F through whichthe liquid travels downward.

It is preferred to make one overflow or of the liquid. The trays D inthe lower of the main compartments and the tray D in the uppercompartment are each preferably divided longitudinally into foursections d, (P, the liquid overflowing fromone to the other. In thelower trays D, D, and D of the lower main compartment, are placed coilsp, p, 10 through which the air to be' separated passes into theapparatus. The outlet or overflow from the lower tray D is provided witha ball tap S actuated by a float s, to allow the liquid under pressureto flow from the deep tray D into the compartj Similar means dement A atthe bottom. scribed hereafter permit of the flow of the liquid from thetray D into the compartment A.

The working process is as follows :The several trays are chargedwithliquid air. The cold dry air at the lowest necessary pressure issimultaneously introduced into the coils q and p, p, p, immersed in theliquid oxygen in the compartment A, and in the liquids rich in oxygen inthe trays D, D, D A part of the liquid in these trays is vaporized *inliquefying a corresponding quantity of the fresh air passing through thecoils. The gas thus vaporized passes up through the pipes E into thetrays above, and the liquid in the lower trays is enriched in oxygen bythe vaporization as the nitrogen is the more volatile gas.

Instead of introducing the cold compressed air only in coils immersed inliquid oxygen it is distributed simultaneously through two, three ormore of the lower trays in order to carry out the liquefaction inliquids as cold as possible, thereby reducing to a minimum the pressureand also the loss of liquefied air, owing to its vaporization whenpoured'into the tray D under a lower pressure. The air liquefied in thecoils is forced upward through the pipes C,

G, by the excess of pressure of the air supply. -A portion of the airliquefied in the lower compartment A, and collected in the pipe isforced through the pipe K, into one of the trays l) of the t1 per maincompartment, the remainder flowing through the valve G and coils H intothe top tray D of the lower main compartment. The liquid air from thepipe K is poured by the pipe K into the tray D in which the liquid hasthe composition of atmospheric air. The greater part of the liquefiedair is led by the pipe G, into the exchanger H formed of ment A is pureoxygen.

three concentric coils, the liquid passing through the intermediatespace from the right to the left and escaping at V, while the gas richin nitrogen evolved from the tray D entering at V travels at the sametime in the exterior and interior coils from the left to the right. Intheir travel upward the gases originally enerated in the trays passthrough the liquids of the several trays in succession.

The gases are split up by the notched edges of the bells, and thus anexchange of a art of the liquid nitrogen for a corresponding quantity ofthe oxygen of the ases is en-' abled to take place. The result 0 thisseries of exchanges is that the liquids flowing downward in the columnbecome richer and richer in oxygen and the gases flowing upward richerand richer in nitrogen; the remaining nitrogen being vaporized in thedivisions of the tray D, so that the liquid flowing by the ball tap intothe bottom compart- This liquid is vaporized in the compartment A andthe gas flows out of the apparatus by the opening 0 to pass into theexchangers, (not shown in the drawing). On the other hand the gaseousmixtures rich in nitrogen flowing out at N under a pressure aboveatmospheric pressure, pass into the exchanger H, formed of twoconcentric coils from the rightto the left of the interior coil and iscooled therein by the nitrogen resulting finally from the separation andwhich travels the exterior coil of the exchanger from the left to theright before its escape through the outlet 4). Then by means of the pipeT this gas is led into the coils g immersed in the liquid in the placebetween the divisions of tray D, and'a part of this liquid is vaporizedin liquefying the gas sent into the coil.

The liquid formed in the coils g is poured by the pipe T at L into thetray D at the top of the apparatus. An exchange takes ases compartment Ban flowing upward, and the liquid of the successive compartments. Theresult is that the gas after having finally passed through the uppercompartment in which the liquid contains about 93% of nitrogen, will beformed of nitrogen of about 98% which flows out of the appaenerated inthe ratus through '0' (to be led into an exchanger not shown). At thesame time nearly all the oxygen of the liquids accumulates in thecompartments B, and the mixture flowing from B into A is richer inoxygen than air.

The composition of this liquid mixture depends upon the number of traysabove B, and upon the. quantity of liquid air coming from the collectingpipe C, and poured by the pipes K, K into the tray D This liquid mixtureflows into A periodically and automatically for instance by means of acombination of a threeway stop tap S and S When the liquid reaches ahigh level the float s shuts the cock S of t e outlet from thecompartment B to the compartment A, and so stops the flow of liquid intothe compartment A. Then the threeway cock S actuated by the float sallowsthe compartment A to communicate with the lower part of thecolumn, where there is a pressure greater than atmospheric pressure.Under the influence of this ressure the valve S opens and the liquid owsthrough the pipe M into that tray of the lower division of theapparatus, in which the composition of the liquid is the same as thecomposition of the liquid flowing from A. In the drawing the pipe M isshown as let into the com artment D When the level of the liquid issufficiently lowered the float s of the threeway cock S puts intocommunication the interiors of the" compartments A and B, the pressurelowers to about the atmospheric pressure, the valve S closes under thepressure from below and the float 8 opens the corresponding cock S,and'allows the liquid to flow again and so on.

To start the apparatus we admit liquid air by the cocks R, R", and whenthe trays of the apparatus up to the compartment D are charged withliquid we close the cock R, and begin to work our apparatus by-sendingthe air coming from the exchangers into the coils p p p and g, and thecock Ris only closed when the liquid rich in nitrogen employed for theseparation of atmospheric air into its elements from liquid air, theseparation has not been complete, a great part of the oxygen of the airtreated being lost and the nitrogen being impure. .By'

our process we obtain a complete separation of the air into itselements. We obtain 92% of the oxygen. of the air treated in ourapparatus in a state of complete purity, and nitrogen of a purity of98%, or by repeating the process the gaseous mixture containing 98% ofnitrogen being again liquefied, we obtain the Whole of the oxygen of theair treated, and absolutely pure nitrogen.

Our invention consists essentially in-effecting a first separation ofthe liquefied air under a pressure above atmospheric pressure, intoliquid rich in oxygen and gaseous mixtures rich in nitrogen,subsequently reliquefying the gaseous mixtures rich in nitrogen andsubmitting them under a lower pressure to a new separation and finallyvaporizing the oxygen, and drawing it off from the apparatus separatelyfrom the nitrogen. And more generally we. can effect several successiverectifications each followed by a new liquefaction of the gaseousmixtures to be further fractionated the last separation only takingplace under the lowest pressure, the others under increasing pressuresfrom the last up to the first.

The second liquefaction is carried out under very advantageousconditions, as for instance, a slight increase of the initial pressureonly is necessary, and as special dehydraters, exchangers, and similardevices are not employed for this reliquefaction there are no losses orinconvenience arising from the use of such devices.

The first separation is advantageously effected by conveniently adaptedrectification combined with partial vaporization, viz., the liquid inthe course of the rectification is submitted to successive vaporizingprovoked by the liquefaction of cold compressed air, so that a part ofthe latter being liquefied in liquids cooler than pure oxygen it allowsof the reduction of the pressure. at which the liquefaction takes place,and moreover the loss of liquid, when poured under a lower pressure isthereby greatly reduced.

The air or mixture to be separated may be totally or partially liquefiedin the first liquefaction. The partial liquefaction yielding a gaseousmixture richer in nitrogen than air, and a liquid mixture richer inoxygen. The gaseous mixture is liquefied along with the gas resultingfrom the first fractionation, which is also liquefied, and the liquidformed from both these gases is submitted to a rectification, and so on.The last liquefaction is always a complete one to increase the purity ofthe nitrogen, and recover more oxygen. The cooling of the air toliquefaction is effected in the exchanger H H by the counter currents ofthe cold gaseous mixtures formed in the fractionating/process.

The hereinbefore described process can be carried into effect by meansof different forms of apparatus based on the same principles and theparts of the apparatus may be varied in their nature and disposition.

By the word rectification we Wish to indicate the operation consistingof putting into a close contact (which has to besufficiently long andextended) a gaseous current of oxygen and nitrogen (to be rectified)with a current of a liquid mixture of oxygen and nitrogen; the gaseousmixture of oxygen and nitrogen being richer in oxygen than the gas whichwould be emitted at the beginning of the vaporization of theliquid-employed for the rectification. By these means a double andprogressive exchange is permitted and caused to take place; the vaporsield up the oxygen they contain to the liquid and this causes thevaporization of an equivalent quantity of the nitrogen of the liquid.

\Ve would have it clearly understood that our process and apparatus areapplicable to the separation of the constituents of any other mixture ofgases as well as for the separation of the constitutents of atmosphericair.

\Vhat we claim as our invention, and desire to protect by Letters Patentis 1. The process of separating oxygen and nitrogen from liquefiedmixtures thereof which consists in vaporizing liquid rich in oxygen,rectifying the gas resulting from the said vaporization by causing it topass upward through layers of liquids richer and richer in nitrogen theliquids progressively enriched in oxygen overflowing downward,

reliquefying the gaseous mixture rlch in nitrogen obtained by the firstrectification by submitting it to a sufficient pressure and causing itto vaporize another portion of the reliquefied mixture and rectifyingthe gas resulting from the said vaporization by means of the reliquefiedmixture.

2. The process of separating oxygen and nitrogen from liquefied mixturesof same comprising (a) liquefying dry cold compressed air by vaporizingliquids rich in oxygen, (6) submitting the gas resulting from the saidvaporization to a rectification by means of the liquefied mixture, (0)reliquefying the gas rich in nitrogen resulting from thefirst-rectitication by causing it to vaporize liquid mixtures of oxygenand nitrogen, and (d) rectifying the gas resulting from the saidvaporization by means of th reliquefied mixture.

3. In the separation of oxygen and nitrogen evolved from areliquefaction of a similar gas by liquefying cold gaseous mixtures ofoxygen and nitrogen and subjecting the gas resulting from the saidvaporization to the rectifying action of liquid mixtures of oxygen andnitrogen less and less rich in oxygen and finally to the rectifyingaction of hquid mixtures richer in nitrogen than atmospheric liquefiedair.

5. In the separation of oxygen and nitrogen by means of a liquefactionof the air and'its rectification, in combination, a first rectification,the reliquefaction of the gas rich in nitrogen resulting from the saidfirst rectification with a further rectification by 15 RENE JACQUESLEVY. ANDRE 'HELBRONNER Witnesses as to Ren Jacques Lvy:

J. OWDEN OBRJEN, H. BARNFATHEB.

Witnesses as to Andr Helbronner:

CAMEILLE CERT,

W. HORR.

